How Long Does Birth Control Take to Work?

The most common and popular choice is commonly known as “the pill.” In fact, there are many different brands and types of birth control pill, and they all function slightly differently.

Despite these variations, all birth control pills work by increasing the amount of hormones in your body to prevent your eggs from leaving your ovaries. Some pills contain only estrogen, others only progestin. Many women use a combination pill which includes both.

No matter which type of birth control pill you choose, it must be prescribed by a doctor.

Your doctor can help you to determine which prescription best serves your needs, considering your past medical history and your goals regarding pregnancy and family planning. For example, women who are breastfeeding another child should not use estrogen pills and will need a progestin-only birth control pill.

Depending on the type of pill you're using, it may take from one to seven days to start working.

If taken within five days after the first day of your regular period, birth control pills are immediately effective. If you wait until after the first five days, Planned Parenthood​ recommends using a “backup” contraceptive, for example a condom with spermicide, during the first week you use birth control.

It's important to take birth control pills at the same time each day for the hormones contained in them to remain effective at preventing pregnancy. If you forget a dose or take it more than three hours late, you should use a condom or another method of birth control for the next two days, until you've returned to your regular birth control schedule.

How long does it take the shot to work?

Some women decide not to use the pill, often because they don't want to keep them around the house or have to remember to take them every day.

Another option for pregnancy prevention is a hormone shot, usually referred to by its brand name: Depo-Provera.

Like hormone pills, the shot works by increasing the amount of progestin in the body. The increased progestin prevents a woman’s eggs from leaving the ovaries, making it impossible to become pregnant.

As with birth control pills, it's recommended that women use a secondary method of birth control for the first seven days. One shot of Depo-Provera will reliably prevent pregnancy for about three months. After twelve weeks, a woman will have to get another shot in order for the birth control effects to continue.

How long does it take an I.U.D.​ to work?

​One much longer lasting form of birth control is an intra-uterine device, called an I.U.D.

Many women and doctors consider this to be the most reliable form of birth control, because it doesn't require you to remember to take a pill each day or make an appointment to get a new shot every three months.

Your doctor can implant an I.U.D. and it will prevent pregnancy for anywhere from three to twelve years depending on the brand and type you choose.

There are two main types of I.U.D: hormonal devices that operate using the same hormones found in birth control pills and hormone shots, and a non-hormonal I.U.D. known as a copper T, or referred to by its brand name: ParaGard.

As with other methods of hormonal birth control, women should continue using a condom to prevent pregnancy during the first seven days after inserting an I.U.D.

ParaGard devices are effective immediately after they are implanted, because they do not use hormones to work. ParaGard devices are made of copper, which inhibits the movement of sperm to prevent pregnancy. Women who are allergic or sensitive to copper or other metals should not use ParaGard.

There are some side effects to using an I.U.D., including bleeding or pain, but these are usually minimal and often will go away after a few days. Sex is no more painful or bothersome when using an I.U.D. than without one, and you can have sex immediately after having an I.U.D. implanted if you choose to.

It's important to remember that no form of birth control prevents sexually transmitted infections. You should get tested regularly and continue practicing safe sex, even while using birth control.​